1. Field of the Invention
The present invention relates to a semiconductor integrated circuit, and more specifically to a semiconductor integrated memory circuit including therein a programmable read only memory (abbreviated "PROM") and having an error correction function.
2. Description of Related Art
In a conventional semiconductor integrated memory circuit including a PROM therein and having art error correction function, when a data bit set composed of a plurality of data bits is written or programmed into a data bit cell set of the PROM, a plurality of check bits are calculated on the basis of the plurality of data bits, and is written into a check bit cell set of the PROM. On the other hand, when data is read out from the PROM, corresponding check bits are also read out from the PROM. A logical processing is performed on the basis of data bits of the read-out data and the read-out check bits, so that if there is an error in the read-out data, the error is corrected.
In the above mentioned conventional semiconductor integrated memory circuit including a PROM therein and having an error correction function, in the case that data is not programmed, each data bit of the PROM is in an erased condition, namely, "1". Therefore, if all bits of a data bit set to be programmed are "1", it is not necessary to program that data bit set. On the other hand, all bits of a check bit set generated on the basis of the data bit set having all bits of "1" become "0" in the conventional semiconductor integrated memory circuit. Therefore, it is necessary to program "0" into a corresponding check bit cell set of the PROM.
Therefore, in the conventional semiconductor integrated memory circuit including a PROM therein and having an error correction function, although a program or data to be programmed includes a number of data bit sets to be written having all bits of "1", since it is necessary to program the check bits, a required total programming time has been long.